If the spec sheet for a 6x4 truck gives a;
‘Standard’ [315 Fronts and 295 Rears] tyre spec
and
‘Optional’ [295 Fronts and 11/225 Rears] tyre spec
Is it possible to use the standard front tyres and optional rears?
The axle weights for the rear axles are the same regardless of which tyres are fitted but the fronts it makes a one-tonne difference to the front axles weight. Can I run 315 fronts and 11/22.5 rears is basically what I’m asking? 
hammer:
If the spec sheet for a 6x4 truck gives a;‘Standard’ [315 Fronts and 295 Rears] tyre spec
and
‘Optional’ [295 Fronts and 11/225 Rears] tyre spec
Is it possible to use the standard front tyres and optional rears?
The axle weights for the rear axles are the same regardless of which tyres are fitted but the fronts it makes a one-tonne difference to the front axles weight. Can I run 315 fronts and 11/22.5 rears is basically what I’m asking?
Hi hammer, AFAIK, it’s not just the tyres that would give you ‘uprated’ status, cos the rest of the axle probably also needs to be up to the higher spec, then there’s the info on the plating certificate to consider…
If it were me, I’d ask the vehicle manufacturer’s nearest authorised workshop. 
dieseldave:
hammer:
If the spec sheet for a 6x4 truck gives a;‘Standard’ [315 Fronts and 295 Rears] tyre spec
and
‘Optional’ [295 Fronts and 11/225 Rears] tyre spec
Is it possible to use the standard front tyres and optional rears?
The axle weights for the rear axles are the same regardless of which tyres are fitted but the fronts it makes a one-tonne difference to the front axles weight. Can I run 315 fronts and 11/22.5 rears is basically what I’m asking?
Hi hammer, AFAIK, it’s not just the tyres that would give you ‘uprated’ status, cos the rest of the axle probably also needs to be up to the higher spec, then there’s the info on the plating certificate to consider…
Hmm. Think you might be right dave, getting a bit complex for my over-heated brain!
The truck is plated at the higher rating (i.e. 7.5t front axle) and is wearing 315 fronts, 295 rears. I’m just a tad confused about why the rear axle limits are the same regardless of which type of rear tyre is fitted? This suggests that only the size of front tyre really makes a difference?
I shall ring the ‘nearest authorised workshop’ in the morning.
This is always good for tyre information, or call the tyre dealer you normally use.
You can use 11/22.5 on the rears because basically they have enough rating for the axle weight. I have just bought a s/h MAN and she has 315s all round and thats on the plate too,MAN at Swindon say that I can put 295s on the rear as they will have enough rating for the job.Are you thinking of getting a bit more weight on Hammer ?
pursy:
You can use 11/22.5 on the rears because basically they have enough rating for the axle weight. I have just bought a s/h MAN and she has 315s all round and thats on the plate too,MAN at Swindon say that I can put 295s on the rear as they will have enough rating for the job.Are you thinking of getting a bit more weight on Hammer ?
315’s all round is an expensive habit Pursy! 
I’ve bought a newer truck and it has 315fronts, 295 rears. My old one has 295fronts, 11.22’s on the back. The 11.22’s are all virtually as new and on ally wheels so I’m keen to swap them to save some weight and some money!
295s wont have enough load capacity for a 7.5ton axle, but as said both 11.00s and 295s have enough load capacity for rear axle (dual wheels).